Heavy ends from cumene production via H.sub.3 PO.sub.4 /Kieselguhr catalysts consists mainly of diisopropylbenzenes and hexylbenzenes. This by-product has a relatively low economic value. Alkylation of these by-products with olefins using a tantalum (V) halide/oxide-inorganic oxide catalyst produces a lubricant composition having a higher viscosity index and a higher flash point than conventionally alkylated similar materials.
In copending application Ser. No. 527,535, filed Aug. 29, 1983, now U.S. Pat. No. 4,489,171, the tantalum (V) halide/oxide-inorganic oxide catalyst used to prepare the compositions of the instant invention is described. In copending application Ser. No. 535,103 filed Sept. 23, 1983, now U.S. Pat. No. 4,463,207, a general alkylation process is described utilizing a tantalum (V) halide/oxide-inorganic oxide catalyst.